Any recommendations on a vacuum pump for LS376-495?

[69camarokid]

I have a 69 Camaro with an LS376-495, TR6060 6-speed in it. The LS376-495 is an LS3 engine with a GM Hot Cam pre installed.

I recently upgraded my brakes from some cheap 11" disc brakes i bought in college to some Wilwood 13" front (6 piston) and 12.2" rear (4 piston).
It has a power brake set up. The issue I am having is that sometimes the pedal is very stiff and the brakes clamp with great force and are awesome!
Other times they need to be tapped first to build up pressure. I am sure there is no air in the lines.

Im told that the cam in the LS3 may be causing a low vacuum and that is leading to the pedal feeling slightly soft form time to time. Ive been recommended
by my mechanic to put in a vacuum pump. Ive never used one of these before and watched a few videos.

I was wondering if anyone had recommendations on a company, or type of vacuum pump, for an LS3?

Thanks for any and all info!

[glr0212]

I'm looking at this too. Stielow used a stock style pump on gunner 20939309.

That seems to be a simple solution. you will need a vacuum switch. I'm in the process of figuring out how to wire it up.

[CSG]

Explain what you mean by needing to tap them. Pad knock back?

[GEARBOXGARAGE]

I have a 69 Camaro with an LS376-495, TR6060 6-speed in it. The LS376-495 is an LS3 engine with a GM Hot Cam pre installed.

This cam is actually pretty mild and should provide plenty of vacuum.

I recently upgraded my brakes from some cheap 11" disc brakes i bought in college to some Wilwood 13" front (6 piston) and 12.2" rear (4 piston).
It has a power brake set up. The issue I am having is that sometimes the pedal is very stiff and the brakes clamp with great force and are awesome!
Other times they need to be tapped first to build up pressure. I am sure there is no air in the lines.

Im told that the cam in the LS3 may be causing a low vacuum and that is leading to the pedal feeling slightly soft form time to time. Ive been recommended
by my mechanic to put in a vacuum pump. Ive never used one of these before and watched a few videos.

I was wondering if anyone had recommendations on a company, or type of vacuum pump, for an LS3?

Thanks for any and all info!

This cam is actually pretty mild and should provide plenty of vacuum. Low or no vacuum would create a hard or stiff pedal and you mention it works great but sometimes goes soft. It sounds more like you are experiencing pad knock back. This is pretty typical on GM rearends with the C-clip style axles as they have end play that can create gaps between the pads and rotors in the rear due to the pistons being "knocked back" into the caliper. You can band-aid the issue by putting in a residual valve. Wilwood has 3 versions, see the following links:

2 lb Pressure residual valve
https://wilwood.com/MasterCylinders/...emno=260-13706

4 lb Pressure residual valve
https://wilwood.com/MasterCylinders/...emno=260-15365

10 lb Pressure residual valve
https://wilwood.com/MasterCylinders/...emno=260-13707

I've seen where people have tested them up to the 10 lb on the street and they create no ill effect with pad dragging or heat build up. I've also used them myself and they do help. I would start with a 4 lb and see if it is minimized. They just go in-line on the rear brake line.

Ideally with solid mounted calipers you want to run a C-clip eliminator or 9" with pressed on/retained bearings so knock back is minimized or run a setup with a floating caliper like the D154's. If you are running hard enough around corners you can also get small amounts of deflection in the front and have a little knock back there as well but that is usually created in autocross situations with sticky tires.

Hope this helps.